freebsd-dev/stand/i386/loader/chain.c
Warner Losh de04d704a9 Use the actual struct devdesc at the start of all *_devdesc structs
The current system is fragile and requires very careful layout of all
*_devdesc structures. It also makes it hard to change the base
devdesc. Take a page from CAM and put the 'header' in all the derived
classes and adjust the code to match.

For OFW, move the iHandle h_handle out of a slot conflicting with
d_opendata. Due to quirks in the alignment rules, this worked.
However changing the code to use d_opendata storage now that it's a
pointer is hard, so just have a separate field for it.

All other cleanups were to make the *_devdesc structures match where
they'd taken some liberties that were none-the-less compatible enough
to work.
2018-03-12 21:39:49 +00:00

135 lines
3.7 KiB
C

/*-
* Copyright 2015 Toomas Soome <tsoome@me.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Chain loader to load BIOS boot block either from MBR or PBR.
*
* Note the boot block location 0000:7c000 conflicts with loader, so we need to
* read in to temporary space and relocate on exec, when btx is stopped.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <stand.h>
#include <sys/param.h>
#include <sys/linker.h>
#include <sys/diskmbr.h>
#include "bootstrap.h"
#include "libi386/libi386.h"
#include "btxv86.h"
/*
* The MBR/VBR is located in first sector of disk/partition.
* Read 512B to temporary location and set up relocation. Then
* exec relocator.
*/
#define SECTOR_SIZE (512)
COMMAND_SET(chain, "chain", "chain load boot block from device", command_chain);
static int
command_chain(int argc, char *argv[])
{
int fd, len, size = SECTOR_SIZE;
struct stat st;
vm_offset_t mem = 0x100000;
struct i386_devdesc *rootdev;
if (argc == 1) {
command_errmsg = "no device or file name specified";
return (CMD_ERROR);
}
if (argc != 2) {
command_errmsg = "invalid trailing arguments";
return (CMD_ERROR);
}
fd = open(argv[1], O_RDONLY);
if (fd == -1) {
command_errmsg = "open failed";
return (CMD_ERROR);
}
len = strlen(argv[1]);
if (argv[1][len-1] != ':') {
if (fstat(fd, &st) == -1) {
command_errmsg = "stat failed";
close(fd);
return (CMD_ERROR);
}
size = st.st_size;
} else if (strncmp(argv[1], "disk", 4) != 0) {
command_errmsg = "can only use disk device";
close(fd);
return (CMD_ERROR);
}
i386_getdev((void **)(&rootdev), argv[1], NULL);
if (rootdev == NULL) {
command_errmsg = "can't determine root device";
return (CMD_ERROR);
}
if (archsw.arch_readin(fd, mem, SECTOR_SIZE) != SECTOR_SIZE) {
command_errmsg = "failed to read disk";
close(fd);
return (CMD_ERROR);
}
close(fd);
if (*((uint16_t *)PTOV(mem + DOSMAGICOFFSET)) != DOSMAGIC) {
command_errmsg = "wrong magic";
return (CMD_ERROR);
}
relocater_data[0].src = mem;
relocater_data[0].dest = 0x7C00;
relocater_data[0].size = SECTOR_SIZE;
relocator_edx = bd_unit2bios(rootdev->dd.d_unit);
relocator_esi = relocater_size;
relocator_ds = 0;
relocator_es = 0;
relocator_fs = 0;
relocator_gs = 0;
relocator_ss = 0;
relocator_cs = 0;
relocator_sp = 0x7C00;
relocator_ip = 0x7C00;
relocator_a20_enabled = 0;
i386_copyin(relocater, 0x600, relocater_size);
dev_cleanup();
__exec((void *)0x600);
panic("exec returned");
return (CMD_ERROR); /* not reached */
}